To devise online advertising strategies of a two-level supply chain influenced by spillover effect and product Web-fit, by taking a two-stage supply chain of one strong manufacturer and two online retailers as the objective, an expected demand model based on spillover effect was constructed, which had considered the features of product Web-fit and online advertising pricing. The equilibrium solutions under four conditions of non-cooperation, cooperation, half-cooperation, and strategic alliance were obtained with game theory, and four equilibrium results were compared. The research showed that under any condition, the wholesale price of the manufacturer was inversely proportional to the product web-fit; the fixed position online advertising investment was directly proportional to the product Web-fit and inversely proportional to the spillover effect, and the total amount of online advertising investment was directly proportional to the product Web-fit. The total profit under the condition of cooperation was usually low and the profit of supply chain members could be maximized by adopting strategic alliance when the product Web-fit exceeded a certain threshold. © 2020, Editorial Department of CIMS. All right reserved.